I am a brand new owner of an ns[pire cx. I am pretty good with computers, not so much with code. I tried entering chens equation as both a function and a program and both times got the error 750 name is not a function.

that is not how I entered it I just typed it this way for readability. I need to be able to enter my value for Tb Tc & Pc and have it solve.
It would be super great if it would ask/print "What is Tb?" "what is Tc?" "what is Pc?"

If someone can help me out and explain how to save it and be able to call it up and use it That would be great! Once I have learned how to do it for 1 equation I can Pete and repeat for the others I need to use. Thank you in advance for anyone willing to take the time to help me out. I will be off and on my computer for the rest of the night (eastern time zone USA)